Advances made in transparent electronics

04/04/2001

SAN DIEGO - Researchers at Oregon State University have made significant advances in the emerging science of transparent electronics, creating transparent "p-type" semiconductors that have more than 200 times the conductivity of the best materials available for that purpose a few years ago.

This basic research is opening the door to new types of electronic circuits that, when deposited onto glass, are literally invisible. The studies are so cutting edge that the products which could emerge from them haven't yet been invented, although they may find applications in everything from flat-panel displays to automobiles or invisible circuits on visors.

"We think these basic advances are very important and are nearing the stage of commercial usefelness," said Arthur Sleight, an OSU professor of chemistry who presented the latest findings today at the annual meeting of the American Chemical Society in San Diego. The research was done in collaboration with principal investigator Janet Tate, an OSU associate professor of physics.

"Our engineers will now take some of these findings and see what type of devices could be created from the new materials," Sleight said. "Transparent electronics is an important new field of technology and should become a growing industry."

Most materials used to conduct electricity are opaque, but some invisible conductors of electricity are already in fairly common use, the scientists said. More complex types of transparent electronic devices, however, are a far different challenge - they require the conduction of electricity via both electrons and "holes," which are positively charged entities that can be thought of as missing electrons. These "p-type" materials will be necessary for the diodes and transistors that are essential to more complex electronic devices.

Only a few laboratories in the world are working in this area, mostly in Japan, the OSU scientists said. As recently as 1997, the best transparent p-type transparent conductive materials could only conduct one Siemen/cm, which is a measure of electrical conductivity. The most sophisticated materials recently developed at OSU now conduct 220 Siemen/cm.

"These are all copper oxide-based compounds that we're working with," Tate said. "Right now copper chromium oxide is the most successful. We'll continue to work with these materials to achieve higher transparency and even greater conductivity."

The advances at OSU are one product of a "focused research group" supported by a $750,000 grant from the National Science Foundation, which is designed to bring together scientists and engineers from different fields to do both basic and applied research, speed the scientific progress and improve the usefulness of findings that emerge from the laboratories of large research universities such as OSU.